Apparatus and method for providing uninterrupted continuous play during a change of sides of a dual sided optical disk

ABSTRACT

An apparatus and method for providing continuous uninterrupted playback of a dual sided optical disk during side-to-side changing of the optical disk. The point at which a dual-sided optical disk will be switched between sides is determined. At some point prior to the switching of sides of the disk, a portion of the data at the end of the first side of the disk is transferred to a memory. During the switching of the disk to the second side, the stored data is read out from the memory to provide uninterrupted continuous playback of the optical disk.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to an optical disk systemfor playing back signals from a recorded media, and more particularly toa video disk apparatus which provides uninterrupted continuous playbackof a dual-sided optical disk during the period of switching from oneside of the disk to the other side of the disk.

[0003] 2. Description of the Related Art

[0004] Generally, optical disks have tracks that can record and playback various types of data. Common optical disks include compact disks(CDs), CD-ROMs, digital video disks or digital versatile disks (DVDs),or other similar disks. Some optical disks, such as DVDs, may be eithersingle-sided or dual sided, i.e., data may be stored on only one or bothsides of the disk.

[0005] In the situation where data is stored on both sides of theoptical disk, the optical disk must be “flipped” from one side to theother in order to read data from both sides of the disk, or the playbackapparatus must be capable of reading both sides of the disk without thedisk being “flipped” over. Generally, a conventional optical diskrecording and playback device uses one optical pickup to record orplayback data on the tracks of a side of the disk adjacent to theoptical pickup. Upon completion of the recording and playback of data onthe side of the disk adjacent to the optical pickup, the disk isflipped, either by human manual intervention or an automatic changingdevice, to access the data from the other side of the disk. The manualflipping of the disk may require that the disk be taken out of theoptical disk recording and playback device and then reinserted back intothe optical disk recording and playback device.

[0006] In the case of an optical disk recording and playback devicewhich has an automatic changing device, a rotatable transfer mechanismmay be used to load a disk to an optical reader. The optical pickup islocated within the optical reader to access the data on the side of thedisk facing the optical pickup. When the first side of the disk has beenread by the optical pickup, the disk will be transferred from theoptical reader back into the transfer mechanism, the transfer mechanismrotated about its axis, and the disk reinserted back into the opticalreader with the second side facing the optical pickup.

[0007] However, there are limitations with respect to the operation ofdevices in which the disk is flipped, either manually or automatically.The reproduction of the video signals must be stopped while the disk isbeing flipped until the data on the second side of the disk can beaccessed. As a result, a video picture is stopped on a screen for theperiod of time required for the disk to be flipped, thus interrupting amovie or game program stored on the disk.

[0008] Alternatively, devices have been developed in which the data onboth sides of an optical disk can be continuously accessed without theneed for manually or automatically flipping the disk. Such devices mayemploy either one or two optical pickups.

[0009] An example of a continuous both-side playback device utilizing asingle pickup is illustrated in U.S. Pat. No. 5,257,111. The singlepickup is adapted to read the video signals recorded on both sides ofthe video disk by moving along a U-shaped track from the center of thetop side of the disk to the center of the bottom side of the disk aroundthe edge of the disk. However, there are limitations associated withthis type of device similar to those in which the disk is flipped.Namely, the reproduction of the of the video signals must be stoppedduring the time the second side of the disk is being accessed, i.e.,while the pickup moves from the outer circumference of the lower side ofthe video disk to the inner circumference of the upper side of the videodisk to read the video signals recorded on the upper side of the videodisk after reading all the video signals recorded on the lower side ofthe video disk. As a result, a video picture is stopped on a screen forabout 10-15 seconds, thus interrupting the movie or game program storedon the disk.

[0010] An example of a continuous both-side playback device utilizingtwo pickups is illustrated in U.S. Pat. No. 5,448,373. A first pickup isprovided to read data from the top side of the disk, and a second pickupis provided to read the data from the lower side of the disk, thusremoving the necessity for flipping the disk. During operation, thevideo disk is rotated in a counter-clockwise direction to read the videosignals recorded on the lower side of the video disk. The rotation isthen halted and reversed to a clockwise direction to read the videosignals recorded on the upper side of the video disk. To overcome theproblem of the time required to reverse the rotation of the video diskfrom the counter-clockwise direction to the clockwise direction(approximately 4-6 seconds) and the resulting stoppage of the videopicture on the screen, both sides of the video disk are read and storedin a memory. The contents of the memory are then output so that thevideo signals from both sides of the disk can be successively reproducedwith no discontinuity. However, this type of device requires anextensive amount of memory space to store the entire contents of bothsides of the disk. The extensive amount of memory required results inboth increased costs for the device and an increase in physical size ofthe device.

[0011] Therefore, although the conventional optical disk systems arecapable of continuous playback of dual-sided optical disks, they do notprovide an apparatus or method for uninterrupted continuous playbackwithout utilizing an extensive amount of memory to store the entire datacontents of both sides of the disk before playback. Thus, there exists aneed for an optical disk system that is capable of continuously playingback signals from a double-sided recorded media without interruptionwhen the side being read is switched, without requiring an extensiveamount of memory space.

SUMMARY OF THE INVENTION

[0012] The present invention overcomes the problems associated with theprior art and provides a unique method and apparatus for providinguninterrupted continuous play of a dual sided optical disk duringside-to-side changing of the disk.

[0013] In accordance with the present invention a portion of the datafrom the end of the first side of an optical disk is read and stored ina memory. During playback of the disk by the system, the data on thefirst side of the disk is read up to the point where the data has beenstored in the memory. When this point has been reached, the datapreviously stored in the memory is read out to the system, and the diskor reading mechanism is simultaneously switched from the first side tothe second side to allow access to data on the second side of the disk.When the data stored in the memory has completed being read out to thesystem, the disk or reading mechanism has already completed the switchfrom the first side to the second side. The data on the second side ofthe disk is then read in succession with the data stored in the memory.Since the data being read by the system does not have to stop during theswitching of sides of the disk, the system provides uninterruptedcontinuous playback of the disk. Additionally, since only a smallportion of the data needs to be stored in a memory, the size of therequired memory location is minimized, thus reducing the hardwarerequirements of the system.

[0014] These and other advantages and features of the invention willbecome apparent from the following detailed description of the inventionwhich is provided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 illustrates in block diagram form an optical disk devicecapable of providing continuous uninterrupted playback of an opticaldisk during side-to-side changing of the disk in accordance with thepresent invention;

[0016]FIG. 2 illustrates in flow chart form a method of providingcontinuous uninterrupted playback of an optical disk during side-to-sidechanging of the disk in accordance with the present invention; and

[0017]FIG. 3 illustrates in block diagram form a system in which theoptical disk device in accordance with the present invention may beutilized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described as set forth in thepreferred embodiment illustrated in FIGS. 1-3. Other embodiments may beutilized and structural, logical or programming changes may be madewithout departing from the spirit or scope of the present invention.

[0019]FIG. 1 illustrates generally in block diagram form an optical diskdevice 100 capable of providing continuous uninterrupted playback of anoptical disk during side to side switching of the disk in accordancewith the present invention. Optical disk device 100 generally includes adisk drive controller 108, a memory device 110, and an optical reader104 for reading an optical disk 102. Optical disk 102 may be a compactdisk (CD), CD-ROM, digital video disk or digital versatile disk (DVD),or the like. A transfer mechanism 106 may be provided for flipping thedisk 102 to access both sides of the disk 102 in the case where it isdual-sided. Alternatively, the optical reader 104 may be able to rotateor may include means for accessing both sides of disk 102 without havingto flip the disk by a transfer mechanism 106, or the device 100 mayinclude any other method of accessing the second side of the disk 102.The data from the disk 102 is processed and output on output line 112,which may connect to an output device 114, such as a video monitor,computer, game device or other device or system which requires the datacontained on optical disk 102.

[0020] Optical disk device 100 operates as follows. Optical disk 102 isinserted into optical reader 104. Optical reader 104 includesconventional sensors and electronics for reading optical disk 102.Controller 108 determines the point at which the reading of disk 102will be switched between sides. Controller 108 may include amicroprocessor. The microprocessor may be any conventional generalpurpose single- or multi-chip microprocessor. In addition, themicroprocessor may be any conventional special purpose microprocessorsuch as a digital signal processor or a graphics processor.

[0021] The time required for the system to switch sides of the disk 102to access the second side of the disk 102, whether it be by transfermechanism 106 or some other means within optical reader 104 or withinthe device 100, is known based on the time required for operation of thetransfer mechanism 106 and may be stored in a ROM within controller 108or programmed directly into controller 108. Controller 108 will cause atransfer of a portion of data from the first side of the disk 102 tomemory device 110. The portion of data transferred may be equivalent toan amount of data that, when read by the system, corresponds to theamount of time required for the optical disk device 100 to access thesecond side of the disk 102. Memory device 110 may be a dedicated memorydevice that is capable of storing the data read from disk 102, or may bepart of a standard computer system allocated to store the data from disk102.

[0022] When the device 100 is activated to playback the disk 102, theoptical reader 104 starts to read data stored on the first side of thedisk 102. When the beginning address of the data that has beentransferred to memory 110 has been reached, the data previouslytransferred from disk 102 to memory 110 will be output by controller108. While the data previously transferred to and stored in memorydevice 110 is being read, optical disk 102 is switched between the firstside and the second side by transfer mechanism 106. Alternatively, iftransfer mechanism 106 is not provided, the second side of disk 102 maybe accessed by any method as known in the art.

[0023] The switching of sides of disk 102 will be completed atapproximately the same time as or before the data stored in memory 110has finished being read, since the amount of data transferred to memory110 will require at least the same amount of time to be read out as ittakes for the device 100 to switch reading between sides of disk 102.This provides for access to the data stored on the second side of disk102 as soon as the data stored in memory 110 has been read out fromdevice 100. For example, controller 108 may be used to monitor theaddress of the data as it leaves memory 110. When the last address ofthe data from the first side of disk 102 stored in memory 110 has beenread out, controller 108 will cause optical reader 104 to commencereading data on the second side of disk 102 with the next sequentialaddress. Thus, in accordance with the present invention, a seamlesstransition from a first side to a second side of an optical disk 102 isprovided without having a video picture stopped on a screen for theperiod of time it takes for the system to switch between sides of thedisk 102. Additionally, since only a small portion of the data stored onthe first side of the disk 102 is transferred to memory 110, the size ofthe memory 110 can be minimized to reduce the physical size and cost ofthe device 100.

[0024] The method for providing uninterrupted continuous playback of adual sided optical disk in accordance with the present invention isillustrated generally at 200 in FIG. 2. In step 210, a dual sidedoptical disk is loaded into an optical reader in any manner as is knownin the art. The optical disk may be a compact disk (CD), CD-ROM, digitalvideo disk or digital versatile disk (DVD), or any other such opticaldisk. The optical reader may be any type of optical reader as is knownin the art, including readers with one or two optical pickups, andincludes conventional electronics and sensors for reading an opticaldisk. Additionally, the optical reader may be used in any type ofapparatus that utilizes any method for accessing both sides of a diskknown in the art, including automatically flipping the disk or providingmeans for reading both sides of the disk without flipping the disk, toname a few.

[0025] When a dual sided optical disk is loaded into the optical reader,the data will typically be read from a first side and then a second sideof the disk consecutively. In step 212, an address representing thepoint at which the reading of data from the optical disk will beswitched from the first side to the second side is determined. Thedetermination of this address point, as further described below, maytypically be performed by a control circuit.

[0026] Once the determination of the point at which the reading of thedisk will be switched between sides has been made in step 212, a portionof the data stored on the first side of the disk is read and transferredto a memory in step 214. The portion of the data transferred includesthe data from the address point determined in step 212 on the first sideof the disk up to and including the point at which the data ends on thefirst side of the disk. The determination of the point at which thereading of the disk will be switched between sides and resulting size ofthe portion of data stored in the memory is typically based on thefunctional capabilities of the optical disk system in which the opticalreader is employed. The amount of data stored in the memory will requirea certain amount of time to be read out from the memory. The amount oftime required to read the data from the memory corresponds to the amountof time required for the optical disk system to switch the reading ofthe sides of the disk to allow access to the data stored on the secondside of the disk. Thus, by varying the amount of data transferred to thememory, the amount of time required for the data to be read out of thememory can also be varied to coincide with the time required to switchsides of the disk.

[0027] For example, the optical disk system may incorporate a transfermechanism that receives the disk after the first side has been played,flips the disk from the first side to the second side, and reinserts thedisk back into the optical reader. Alternatively, the disk may beremoved from the optical reader, the optical reader rotated about anaxis, and the disk reinserted so the optical pickup faces the secondside of the disk. This process may take a number of seconds, such as forexample, 10 seconds. The determined address point on the disk at whichpoint the reading of the optical disk will be switched between sides andthe resulting portion of data to be stored in memory will be someaddress point prior to or equivalent to the address point at which thereis 10 seconds of data left on the first side of the disk, such as forexample 12 seconds. Thus, the size of the portion of data from the firstside of the disk that is transferred to the memory may correspond to theamount of time required for the optical disk system to access the secondside of the disk. Since the amount of time required to switch thereading of the data from the first side of the disk to the second sideof the disk is known, the address point at which to start the datatransfer can be easily determined by a controller in the system.

[0028] In step 216, the system starts to read the data from the firstside of the disk. The data is read by conventional sensors andelectronics for reading an optical disk included in the optical reader.In step 218, the system determines whether the address of the determinedpoint from which the data on the first side of the disk has beentransferred to the memory has been reached. If the determined addresshas not been reached, the method continues reading the data from thefirst side of the disk in step 216. If the address of the determinedpoint has been reached, the data that was previously transferred to thememory in step 214 is read out to the system. While the data previouslytransferred to the memory is read to the system in step 214, the readingof the disk is switched between sides in step 222.

[0029] The switching between sides of the reading of the disk in step222 will be completed at approximately the same time as or before thedata stored in the memory has finished being read in step 220, since theamount of data transferred to the memory will require at least the sameamount of time to be read out as it takes for the system to switchreading between sides of the disk. This provides for access to the datastored the second side of the disk as soon as the data stored in thememory has been read out to the system. When the data stored in thememory has been read out to the system, the data from the second side ofthe disk is read in step 224.

[0030] Since data was read from the memory during the switching of theside of the disk being read, the data appears at a video screen whichrequires the output of the optical disk system to be continuous anduninterrupted. Thus, the method according to the present inventionprovides a seamless transition from a first side to a second side of anoptical disk without having a video picture stopped on a screen for theperiod of time it takes for the system to switch reading the databetween sides of the disk. Additionally, since only a small portion ofthe data stored on the first side of the disk is transferred to thememory, the size of the memory can be minimized to reduce the physicalsize and cost of the device.

[0031] It is important to note that while the embodiment as describedabove determines the point at which the disk is to switch the reading ofsides and transfers a portion of the data at the end of the first sideof the disk before the data is read from the first side of the disk, theinvention is not to be so limited. The determination of the point atwhich the disk will be switched between sides in step 212 and thetransferring of the data to the memory in step 214 can occur at any timeafter the disk has been loaded into the optical reader, as long as it isperformed prior to the time the point determined in step 212 has beenreached in step 218.

[0032]FIG. 3 illustrates in block diagram form a processor system 300 inwhich an optical disk device according to the present invention may beutilized. Such a system could include a computer system, stereo system,video game system, or a television system, all of which can utilize thepresent invention.

[0033] A processor system, such as a computer system for example,generally comprises a central processing unit (CPU) 302 thatcommunicates with an input/output (I/O) device 304 over a bus 320. Asecond I/O device 306 may also be provided. I/O devices 304, 306 may be,for example, a video display or speaker. An optical disk device 308 forreading data stored on an optical disk 301 also communicates with thesystem over bus 320. Optical disk device 308 may also be combined with aprocessor, such as a CPU, digital signal processor or microprocessor, ina single integrated circuit. The processor system 300 also includes amemory 310.

[0034] Processor system 300 is capable of providing continuousuninterrupted playback of a dual sided optical disk utilizing the methodof the present invention as described with respect to FIG. 2. CPU 302will determine a point at which reading of dual sided optical disk 301by optical disk device 308 win be alternated between sides, and cause aportion of the data stored on the first side of the optical disk 301 tobe read and stored in memory 310. When the data from the optical disk301 is being read, the data stored in memory 310 will be read out to thesystem during the time the reading of optical disk 301 is switchedbetween sides, thus providing continuous uninterrupted playback ofoptical disk 301.

[0035] Reference has been made to preferred embodiments in describingthe invention. However, additions, deletions, substitutions, or othermodifications which would fall within the scope of the invention definedin the claims may be found by those skilled in the art and familiar withthe disclosure of the invention. Any modifications coming within thespirit and scope of the following claims are to be considered part ofthe present invention.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A method for reading a first and second side ofa dual sided optical disk comprising: determining a point when readingsaid dual sided optical disk should be switched from said first side tosaid second side; storing a portion of data from said first side of saiddual sided optical disk in a memory, said portion of data comprisingdata from said determined point on said first side of said dual sidedoptical disk up to an end of said first side of said dual sided opticaldisk; reading data from said first side of said dual sided optical disk;switching said reading of said dual sided optical disk from said firstside to said second side when said determined point has been reached;and reading said data from said first side of said dual sided opticaldisk stored in said memory while said switching is occurring.
 2. Themethod according to claim 1, wherein said portion of data corresponds toan amount of time required to switch said reading of said dual sidedoptical disk from said first side to said second side.
 3. The methodaccording to claim 2, wherein reading said data stored in said memorytakes an amount of time approximately equal to said amount of timerequired to switch said reading of said dual sided optical disk fromsaid first side to said second side.
 4. The method according to claim 2,wherein reading said data stored in said memory takes an amount of timegreater than said amount of time required to switch said reading of saiddual sided optical disk from said first side to said second side.
 5. Themethod according to claim 1, further comprising: reading data from saidsecond side of said dual sided optical disk after said data stored insaid memory has been read.
 6. The method according to claim 1, whereinsaid switching further comprises: using a transfer mechanism to flipsaid dual sided optical disk.
 7. The method according to claim 1,wherein said switching further comprises: rotating an optical readerused to read said dual sided optical disk.
 8. The method according toclaim 1, wherein said switching further comprises: moving an opticalpickup from said first side of said dual sided optical disk to saidsecond side of said dual sided optical disk.
 9. The method according toclaim 1, wherein said switching further comprises: using a first opticalpickup to read said first side of said dual sided optical disk; andusing a second optical pickup to read said second side of said dualsided optical disk.
 10. The method according to claim 1, wherein saiddetermining a point when said reading said dual sided optical disk willbe switched is performed by a disk drive controller.
 11. The methodaccording to claim 10, wherein said determining a point when saidreading said dual sided optical disk will be switched includes using amicroprocessor in said disk drive controller to determine a point whensaid reading said dual sided optical disk will be switched.
 12. Themethod according to claim 1, wherein said storing a portion of said datain a memory includes storing a portion of said data in a dedicatedmemory device adapted to store said data from said dual sided opticaldisk.
 13. The method according to claim 1, further comprising:outputting said data read from said dual sided optical disk to an outputdevice.
 14. A method for providing uninterrupted continuous playback ofdata read from a first and second side of a dual sided optical diskcomprising: storing a portion of data from said first side of said dualsided optical disk in a memory; reading data not included in saidportion of data stored in said memory from said first side of said dualsided optical disk; reading said portion of data stored in said memoryafter reading said data not included in said portion of data stored insaid memory; switching said dual sided optical disk from said first sideto said second side concurrently with said reading said portion of datastored in said memory; and reading data from said second side of saiddual sided optical disk after reading said portion of data stored insaid memory.
 15. The method according to claim 14, wherein said storinga portion of data includes storing a portion of data corresponding todata located at an end of said first side of said dual sided opticaldisk.
 16. The method according to claim 14, wherein said storing aportion of data from said first side of said dual sided optical disk ina memory further comprises determining an amount of data to be includedin said portion of data from said first side to be stored in saidmemory.
 17. The method according to claim 16, wherein said determiningincludes using a processor to determine an amount of data to be includedin said portion.
 18. The method according to claim 16, wherein an amountof time required to read said data included in said portion of datastored in said memory corresponds to an amount of time required toswitch said dual sided optical disk from said first side to said secondside.
 19. The method according to claim 14, wherein said switching saiddual sided optical disk further comprises flipping said dual sidedoptical disk from said first side to said second side.
 20. An apparatusfor reading a first and second side of a dual sided optical diskcomprising: an optical disk reader; a memory connected to said opticaldisk reader; and a controller connected to said optical disk reader andsaid memory, said controller causing a portion of data from said firstside of said disk to be read from said disk and stored in said memoryand later read from said memory during a time when reading said disk isswitched from said first side to said second side, thereby providinguninterrupted continuous playback of said dual sided optical disk. 21.The apparatus according to claim 20, wherein said controller determinesa point on said first side of said disk when reading said dual sidedoptical disk should be switched from said first side to said secondside.
 22. The apparatus according to claim 21, wherein said portion ofdata stored in said memory comprises data from said determined point onsaid first side of said dual sided optical disk up to an end of saidfirst side of said dual sided optical disk.
 23. The apparatus accordingto claim 20, wherein said dual sided optical video disk is a DVD. 24.The apparatus according to claim 20, further comprising: a transfermechanism to flip said dual sided optical disk from said first side tosaid second side.
 25. The apparatus according to claim 20, wherein saidoptical disk reader rotates around an axis.
 26. The apparatus accordingto claim 20, wherein said optical disk reader further comprises: anoptical pickup, said optical pickup being adapted to move from saidfirst side of said dual sided optical disk to said second side of saiddual sided optical disk to switch reading from said first side to saidsecond side.
 27. The apparatus according to claim 20, wherein saidoptical disk reader further comprises: a first optical pickup to readdata from said first side of said dual sided optical disk; and a secondoptical pickup to read data from said second side of said dual sidedoptical disk.
 28. The apparatus according to claim 21, wherein saidcontroller comprises a microprocessor.
 29. The apparatus according toclaim 20, wherein said memory is a dedicated memory device adapted tostore data from said dual sided optical disk.
 30. The apparatusaccording to claim 20, further comprising: an output device connected tosaid controller to output said data read from said dual sided opticaldisk.
 31. The apparatus according to claim 30, wherein said outputdevice is a video display device.
 32. An optical disk device forproviding continuous uninterrupted playback of a dual sided opticaldisk, said device comprising: an optical reader for reading said dualsided optical disk; a memory adapted to store data transferred from saiddual sided optical disk; and a controller, said controller determining aportion of data on said first side of said disk to be transferred tosaid memory, wherein said optical reader reads data on said first sideof said disk up to said portion of data transferred to said memory, saidportion of said data transferred to said memory is read while saidsecond side of said disk is accessed, and said second side of said diskis read after said portion of said data transferred to said memory hasbeen read.
 33. The optical disk device according to claim 32, whereinsaid optical reader is rotatable to allow access to said second side ofsaid dual sided optical disk.
 34. The optical disk device according toclaim 32, further comprising: a transfer mechanism to flip said opticaldisk from said first side to said second side to enable said opticalreader to read data from both sides of said disk.
 35. The optical diskdevice according to claim 32, wherein said dual sided optical disk is aDVD.
 36. A system for playing an optical disk comprising: a processor; amemory connected to said processor; an output device; and an opticaldisk device, said optical disk device comprising: an optical readercapable of reading a dual sided optical disk, said processor causing aportion of data from a first side of said dual sided optical disk to beread from said disk and stored in said memory and later read from saidmemory during a time when reading said disk is switched from said firstside to a second side, thereby providing uninterrupted continuousplayback of said dual sided optical disk.
 37. The system according toclaim 36, wherein said processor determines a point when reading saiddual sided optical disk should be switched from said first side to saidsecond side.
 38. The system according to claim 37, wherein said portionof data stored in said memory comprises data from said determined pointon said first side of said dual sided optical disk up to an end of saidfirst side of said dual sided optical disk.
 39. The system according toclaim 38, wherein an amount of time required to read said portion ofdata stored in said memory corresponds to an amount of time required toswitch reading of said dual sided optical disk from said first side tosaid second side.
 40. The system according to claim 36, wherein saidoptical disk is a DVD.
 41. The system according to claim 40, whereinsaid output device is a video display device.
 42. The system accordingto claim 36, wherein said system is a video game system.
 43. The systemaccording to claim 36, wherein said system is a television system. 44.The system according to claim 36, wherein said system is a computersystem.